1. Field of the Invention
The present invention relates to near net shape fabrication using additive manufacturing techniques. More specifically, the present invention relates to adding exterior members and fitments to oilfield tubulars using energy beam and wire feedstock layered material deposition technology.
2. Description of the Related Art
The use of near net shape fabrication by layered deposition of metal is a developing technology that continues to advance through technical challenges. The inventor of the present invention also holds U.S. Pat. No. 7,073,561 for SOLID FREEFORM FABRICATION SYSTEM AND METHOD issued on Jul. 1, 2006, the disclosure of which is hereby incorporated by reference. The teachings of the '561 patent principally address solid member fabrication where the entire fabricated item is comprised of the feedstock wire that is deposited in fusion bonded layers, usually onto some type of a mold. As such, the fabricated item is made of 100% feedstock material, which has some level of uniformity and strength and other predictable parameters.
Another area of advancement in metal deposition technology is the potential use of the technology to add additional members and fitments to an existing structure. For example, in the case of oil and gas drilling and production operations, the well casing, tubing, pipes and rods used (collectively “tubulars”), often times require the attachment of exterior fixtures and other members during operation. Examples of such fitments are collars, flanges, spacers, flow vanes, bore centralizers, stop collars, scratchers, wipers, and other fitments as are known to those skilled in the art.
While adding exterior fitments may appear to be a straightforward process, not unlike the aforementioned additive manufacturing processes, there are new technical challenges. Particularly in the situation where the existing member is a structural member, as all down-hole tubulars are, that has specific and critical engineering parameters required for its use in its intended application. For example, the structural member may have specified dimensional, strength, dynamic, wear, and operating temperature requirements and limitation. It will be appreciated that additive manufacturing requires the heating, melting and solidification of portions of such a member, and that these actions can materially alter the original engineered parameters. Thus it can be appreciated that there is a need in the art for a system and method of additive manufacturing where an original structural member having engineered parameters is not materially degraded during the deposition and layering processes.